We report efficient interface engineering to realize high-performance fully inkjet-printed organic thin-film transistor
(OTFTs) and their applications. By depositing an organo-compatible end-functionalized polystyrene (PS) layer between
organic semiconducting layers and inkjet-printed metallic or conductive polymer contacts, simultaneously, well-ordered
crystals of organic semiconductors and reduced contact resistance were delivered, resulting in much improved carrier
transport and carrier injection abilities. These results may be attributed to the introduction of organo-compatible surface
properties that requires less activation energy for carrier transport and carrier injection. This methodology is compatible
to high-speed and low-temperature printing technologies, therefore it can pave a promising route for realizing high-performance
printed thin-film devices including TFTs, sensors, and light-emitting device applications.